This invention generally relates to a method and apparatus for changing spinal alignment to treat spinal column deformity.
Human spines are formed from vertebrae spaced by intervertebral discs arranged in a gently curving column. Viewed from the side, the column has several curves defining different regions of the spine. Abnormal spinal curvatures occasionally occur in individuals. These abnormal curvatures of the spine include scoliosis (lateral curvature), kyphosis (exaggerated curvature usually in an upper portion of the spine), lordosis (exaggerated curvature usually in a lower portion of the spine), and combinations of these conditions. Although these abnormal curvatures may be cosmetically undesirable, in some cases they can lead to organ problems, reduce mobility of the individual and cause significant pain. Thus, correction of the abnormal spinal curvatures is frequently desirable.
Spinal column deformities are treated with a variety of approaches. In some cases, spinal implants are used to rigidly fix the vertebrae relative to one another. When the vertebrae are held in a rigid position and bone graft material is added, the vertebrae fuse leading to loss of spinal mobility and potentially accelerating degeneration of areas of the spine adjacent the fused portion. Thus, fusion is undesirable in many cases, and there is a need for a method and apparatus for correcting abnormal spinal curvatures without fusing vertebrae.
Because the abnormally curved spines can be out of alignment laterally, as well as forward and rearward, there is a need for a method and apparatus enabling surgeons to modify spinal column alignment simultaneously in multiple directions. Most conventional methods for treating spinal column deformities without fusion are only capable of correcting alignment in one direction at a time. Further, it is generally recognized that corrective methods and apparatus should be minimally invasive to reduce an opportunity for complications during and following the procedures, and to reduce healing times. In addition, there is a need for a method and apparatus allowing progressive adjustment of vertebrae to obtain a desirable optimal alignment of the spinal column for the patient.